Fume-collecting hood for electric furnace



April 12, 1960 D. w. PIERCE FUME-COLLECTING HOOD FOR ELECTRIC FURNACE Filed Dec. 19, 1958 3 Sheets-Sheet l //V VE N T01? 04 VII? W. P/ERCE r &4; M571 Attorney April 12, 1960 o. w. PIERCE FUME-COLLECTING HOOD FOR ELECTRIC FURNACE 19, 1958 3 Sheets-Sheet 2 Filed Dec.

l/VVE/VTOR DAV/D n. P/ERCE Af/orney April 12; 1960 I w plERCE 2,932,679

FUME-COLLECTING HOOD FOR ELECTRIC FURNACE Fi led Dec. 19, 1958 3 Sheets-Sheet 3 INVEW TOR DA l/ID W. PIERCE United States Patent David W. Pierce, Homewood, Ill., assignor to United States Steel Corporation, a corporation of New Jersey Application December 19, 1958, Serial No. 781,520

Claims. (Cl. 13-9) This invention relates to a hood adapted to be placed over an electric furnace to collect the fumes escaping through the roof thereof.

Normal operation of an electric furnace produces heavy fumes in great volume which escape through the electrode ports in the roof and accumulate in the furnace shop since the volume is beyond the capacity of usual ventilating means. This produces almost intolerable working conditions in the shop, particularly during certain portions of the refining cycle. It is accordingly one object of my invention to provide means for collecting the objectionable fumes and conducting them to an exhaust stack. A further object is to provide a fume-collecting hood requiring a minimum volume of air flow to sweep the fumes therefrom to the stack.

In general terms my fume-collecting hood comprises a cover of metal plate having a cylindrical side wall, open at the bottom and a flat top or deck, constructed of metal plate and structural sections. The deck has a central window to permit lowering of the electrodes through the usual ports in the furnace roof and the window is fitted with removable closures fully filling it. The closures have electrode ports therein and refractory spacer rings closing the spaces around the electrodes except for a small clearance. An outlet duct extends from one side of the hood to an exhaust fan and an air-inlet pipe extends into the hood radially from a point on the wall thereof spaced circumferentially from the outlet duct.

A complete understanding of the invention may be obtained from the following detailed description and ex planation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawings:

Figure l is a plan view;

Figure 2'is a vertical section taken along the plane of line II-II of Figure 1;

Figure 3 is a partial plan view to enlarged scale, with parts removed;

Figure 4 is a partial section taken along the plane of line IV-IV of Figure 3;

Figure 5 is a section through a modified closure like that of Figure 4; and

Figure 6 is a partial radial section through the hood showing a centering post on the furnace roof.

Referring now in detail to the drawings and, for the moment to Figures 1 and 2, an electric furnace has a cylindrical side wall 10 and a dome roof 11 removably disposed thereon. The wall and roof are constructed of refractory brick, the roof brick being laid with a confining marginal ring 12 and the wall brick within a metalplate binding 13. T-section posts'14 extend upwardly from ring 12 at points spaced circumferentially thereof,

for engagement by crane hooks to lift the roof.

The hood of my invention, designated generally by numeral 15, is fabricated of welded-plate construction and comprises a cylindrical side wall 16, a circularfiat deck or top 17 thereon and radial webs 18 welded to the wall and top. Channel-section beams 19 are laid on deck 17 in a generally triangular configuration and welded thereto. Intermediate beams 20 extend between beams 19 in a similar arrangement, approximately bounding a generally triangular window opening 21 in the deck, with arcuate corners. Opening 21 is dimensioned to admit the usual group of three furnace electrodes and is defined by a marginal rim welded to deck 17 composed of a flat bar 22 and an angle 22a welded to the bar. 1- section radial ribs 23 extend at right angles from each beam 20 and are welded together at the center of the opening. This weldment is removably supported on seats 23b. Ribs 23a extend between rim 22 and beams 19 and 2% The hood is adapted to'be positioned coaxially of the roof by posts 14.

Three pentagonal closures 24 are removably disposable in opening 21, completely filling it. Each closure has a marginal frame 25, fabricated from angles, resting on ribs 23 and 22a and a central ring 26, supported thereon by radial webs 27, defining an electrode port. A spacer ring 28 of refractory material seated in the electrode port is cast within ring 26, as shown in Figure 5 or is preformed and removably supported on angle brackets 29 secured to the ring as shown in Figures 3 and 4. A working-deck plate 3% is laid on beams 19 and 29.

A duct 31 extends from a point on side wall 16 to a suitable exhaust fan. An air inlet pipe 32 extends inwardly from another point on said wall to opening 21. Pairs of spaced centering guide rails 33 are secured vertically to said wall for cooperation with the webs of posts '14 when placing the hood on the furnace roof.

It will be apparent that the hood of my invention is simple in construction yet durable and relatively inexpensive to fabricate. In use it has proved highly effective in ridding the electric furnace shop of air pollution by noxious fumes, at a very low operating cost. The hood may be easily disconnected from the exhaust fan when it has to be removed to permit removal of the furnace roof and is easily replaced on the furnace and reconnected to the stack.

Although I have disclosed herein the preferred embodiment of my invention, I intend to cover as well any change or modification therein which may be made without departing from the spirit and scope of the invention.

i claim:

1. A hood for the roof of an electric furnace comprising a cylindrical side wall having a diameter such as to fit on said roof and a circular fiat deck carried by said wall, said deck having a window therein dimensioned to clear a group of electrodes inserted vertically through said roof, a plurality of polygonal closures removably disposable on the deck so that, together they substantially fill said opening, each closure having an electrode port therein and a refractory spacer ring seated in said port.

2. Apparatus as described in claim 1, characterized by said closures abutting each other along one edge.

3. Apparatus as described in claim 1, characterized by a plurality of beams disposed on said deck as chords and a frame for said opening carried by said beams.

4. Apparatus as described in claim 1, characterized by said spacer rings being removably disposed on said closures.

5. A fume-collecting hood for an electric furnace comprising an open-bottomed chamber dimensioned to overlie the furnace, said chamber having a window opening therein dimensioned to admit a group of electrodes insertable through the furnace roof, a plurality of polygonal closures fitting together in said opening and symmetrically disposed around the center thereof, each closure having an electrode port therein and a refractory spacer ring seated in said port.

(References on following page) References Cited in the file of this patent 1,922,312

2,672,491 UNITED STATES PATENTS 2,761,003 783,736 Seward Feb. 28, 1905 1,018,727 Ruthenberg Feb. 27, 1912 5 1,234,946 Sperling July 31, 1917 198,255

Manfield Aug. 15, 19 33 Lamb -1- Mar. 16, 1954 Richards Aug. 28, 1956 FOREIGN PATENTS Switzerland Sept. 1, 1938 

